1. Field of the Invention
The present invention relates to an image forming apparatus such as a printer, a copier, a facsimile machine or a composite apparatus having functions of these apparatuses.
2. Description of the Background Art
An image forming apparatus has been known which is provided with a charging device including a charging roller for charging the outer circumferential surface of a photoconductive drum by synchronously rotating with the photoconductive drum and a brush roller for cleaning toner particles, additives and the like attached to the charging roller by coming into contact with this charging roller substantially from right above. Here, the brush roller comes into contact with the charging roller due to its own weight and is rotated by the charging roller (see, for example, Japanese Unexamined Patent Publication No. 2005-4065).
However, since the brush roller is rotated by the charging roller according to the above background art, it has a weak cleaning force and cannot be expected to have a long life of enduring about several hundred thousands image forming operations. Accordingly, it may be thought to make the brush roller heavier in order to strengthen the cleaning force. However, according to such a measure, there are problems that charging performance is reduced because additives are fixed to the charging roller and jitter images (line images) are likely to be formed because the rotation of the charging roller becomes unstable.